The present invention relates to a synthetic resin sheet having a notching strip and a sheet container formed of the synthetic resin sheet and, more particularly, to a synthetic resin sheet which can be smoothly and clearly divided by the notching strip and the container formed of the sheet.
There is a synthetic resin sheet formed by integrally molding by coextruding means a sheet body and a notching strip in the state that the sheet body is divided by the notching strip into right and left side sheet body portions and the notching strip is interposed between the right and left side sheet body portions, and a container such as a bag or a tubular container is formed of the sheet.
The conventional synthetic resin sheet with a notching strip of this type is necessary to be held in the state that the bonding strengths between the sheet body portions and the notching strip are sufficiently high so that the mechanical strength of the entire sheet is sufficiently high until the sheet main body portions are separated through the notching strip, and is also required to have convergent function of disabling to increase the bonding strength between the sheet body portions and the notching strip so that the separating operation of the sheet body portions of the sheet may be smoothly and reliably achieved through the notching strip.
Thus, the synthetic resin sheet with the notching strip of this type has been relatively increased in the bonding strength between the sheet main body portions and the notching strip to satisfy the abovementioned contradictory required matters, has been increased in the hardness of the notching strip itself higher than those of the sheet body portions to thereby enhance the mechanical strength of the entire sheet, and has been separated between the sheet body portions by damaging the bondings between the sheet body portions and the notching strip by special means such as bending.
However, a considerably large force is necessary to separate the bonding between the sheet body portions and the notching strip in the above-described conventional sheet. Thus, the separating operation of the entire sheet is extremely difficult to perform. Further, a number of unnecessary synthetic resin pieces of yarn shape have been formed at the end faces of the separate sheet body portions from the notching strip to causing an unpleasant feel to its user.
The hardness of the notching strip has been raised to sufficiently enhance its mechanical strength, but since the strip has thus become mechanically brittle, the strip has readily been broken when the entire sheet is separate by pulling the strip, and a drawback might occur in that the overall sheet cannot be separated into the respective sheet body portions and the strip.
When a sheet container is, further, formed by a thermal molding method such as vacuum molding or pneumatic molding with the synthetic resin sheet with the notching strip, the bonding strengths between the sheet body portions and the notching strip are largely increased by the thermal action on the sheet at the thermal molding time, thereby disabling to manually separate between the sheet body portions and the notching strip of the sheet. Therefore, the thermally molded container of the synthetic resin sheet with the notching strip could not be heretofore formed.